US defence secretary Chuck Hagel was challenged by a Chinese general Saturday to better explain the US military's Asia pivot, just moments after the Pentagon chief warned Beijing over cyberwarfare.

In a speech at a high-profile security conference in Singapore, Hagel said the US administration has concerns about "the growing threat of cyberintrusions, some of which appear to be tied to the Chinese government and military".

The rebuke – coming in China's backyard and in front of a Chinese delegation – was countered by questioning of America's intent in the region, following a reposition of its military strategy.

Major General Yao Yunzhu, director of the Center for China-America Defense Relations at the People's Liberation Army's Academy of Military Science, challenged Hagel to better explain America's military buildup across the region.

"Thank you for mentioning China several times," she said in the question-and-answer session after Hagel's speech.

She said the Obama administration's new focus on the Pacific has been widely interpreted as an "attempt to counter China's rising influence and to offset the increasing military capabilities of the Chinese PLA. However, China is not convinced."

In pointed remarks, she asked Hagel how he can assure China that the increased US deployments to the region are part of an effort to build a more positive relationship with Beijing.

"That's really the whole point behind closer military-to-military relationships," Hagel responded. "We don't want miscalculations and misunderstandings and misinterpretations. And the only way you do that is you talk to each other."

The Pentagon chief said the US welcomed a strong and emerging China that takes on responsibilities for security in the region, adding that the two countries have to be inclusive and direct with each other. "I think we've made continued progress," he said. "And we'll make more progress."

The comments come ahead of a meeting next week in California between President Barack Obama and Chinese President Xi Jinping. It will be their first meeting since Obama's re-election and Xi's promotion to Communist Party chief.

Cybersecurity is likely to be a focus of the heads of state meeting, following a spate of hacking attacks on US firms and news organisation that have been blamed on Beijing.

On Friday, it is believed Hagel raised the prospect of forming a cyberworking group in sideline talks with Chinese officials.